Earlier quoted context omitted.
Formality of environment need not extend to dress code. Remember, dress codes are used against women (by men telling the woman how she should be dressing) far more often than they are men. You can have a formal office without a formal dress code. Yesterday I wore jeans, a t-shirt, chucks and a blazer to work at a formal company. I only wear the blazer because I am physically small and look young, so I feel it enhance…
It does help though. It doesn't need to be overly formal, but putting on nice slacks and a nice shirt with dress shoes helps you go "I am at work. This is different than when I wear my casual clothes. These people are my colleagues and not my friends/family." I'm not saying that it is solely down to the clothes, but that small bit of separation helps.
I feel restricted / unnatural and generally unhappy if I have to wear those sort of clothes.
I've noticed a lot of people in the current generation wearing more formal clothes at work, I guess this is a cycle, and us 40ish year olds in T-shirts were doing the opposite of those who came before.
Honestly I find it weird to hear what seems like quite young guys on the train to work having a conversation about the best shoe polish.